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FIR VIEW OF DISKS OF WEAK-LINE T TAURI STARS
SATOSHI TAKITA,YASUO DOI,KO ARIMATSU,TAKAFUMI OOTSUBO 한국천문학회 2017 天文學論叢 Vol.32 No.1
We have observed $\sim$60 Weak-line T Tauri stars (WTTSs) toward the Chamaeleon star forming region using the AKARI Far-Infrared Surveyor (FIS) All-Sky maps. We could not detect any significant emission from each source even at the most sensitive WIDE-S band. Then, we have performed stacking analysis of these WTTSs using the WIDE-S band images to improve the sensitivity. However, we could not detect any significant emission in the resultant image with a noise level of 0.05~MJy~sr$^{-1}$, or 3 mJy for a point source. The three-sigma upper limit of 9~mJy leads to the disk dust mass of 0.01~M$_{\oplus}$. This result suggests that the disks around Chamaeleon WTTSs are already evolved to debris disks.
Keiichi Nakahara,Satoshi Yamashita,Katsumasa Ideo,Seigo Shindo,Tomohiro Suga,Akihiko Ueda,Shoji Honda,Tomoo Hirahara,Masaki Watanabe,Taro Yamashita,Yasushi Maeda,Yasuhiro Yonemochi,Tomohiro Takita,Yuk 대한신경과학회 2014 Journal of Clinical Neurology Vol.10 No.4
Background Listeria monocytogenes (L. monocytogenes) is a rare causative pathogen ofbrain abscess that is often found in immunocompromised patients. Although patients with supratentorial listerial abscesses showed a longer survival with surgical drainage, the standardtherapy for patients with subtentorial lesions has not been established. Case Report We report herein a patient with supra- and subtentorial brain abscesses causedby L. monocytogenes infection. These abscesses did not respond to antibiotics, and his symptoms gradually worsened. Drainage was not indicated for subtentorial lesions, and the patientwas additionally treated with hyperbaric oxygen therapy, which dramatically reduced the volume of abscesses and improved the symptoms. Conclusions This is the first report of drastic therapy for a patient with listerial brain abscesses involving combined antibiotics and hyperbaric oxygen therapy. The findings suggestthat hyperbaric oxygen therapy is a good option for treating patients with deep-seated listerialabscesses and for who surgical drainage is not indicated.
ADVANTAGES OF THE AKARI FIR ALL-SKY MAPS
YASUO DOI,SATOSHI TAKITA,TAKAFUMI OOTSUBO,KO ARIMATSU,MASAHIRO TANAKA,TAKAHIRO MORISHIMA,MITSUNOBU KAWADA,SHUJI MATSUURA,YOSHIMI KITAMURA,MAKOTO HATTORI,TAKAO NAKAGAWA,GLENN WHITE,NORIO IKEDA 한국천문학회 2017 天文學論叢 Vol.32 No.1
We present the {\it AKARI} far-infrared (FIR) all-sky maps and describe its characteristics, calibration accuracy and scientific capabilities. The {\it AKARI} FIR survey has covered 97\% of the whole sky in four photometric bands, which cover continuously 50--180 micron with band central wavelengths of 65, 90, 140, and 160 microns. The data have been publicly released in 2014 \citep{2015PASJ...67...50D} with improved data quality that have been achieved since the last internal data release \citep{2012PKAS...27..111D}. The accuracy of the absolute intensity is $\leq10$\% for the brighter regions. Quantitative analysis of the relative intensity accuracy and its dependence upon spatial scan numbers has been carried out. The data for the first time reveal the whole sky distribution ofinterstellar matter with arcminute-scale spatial resolutions at the peakof dust continuum emission, enabling us to investigate large-scaledistribution of interstellar medium in great detail. The filamentarystructure covering the whole sky is well traced by the all-sky maps. We describe advantages of the AKARI FIR all-sky maps for the study of interstellar matter comparing to other observational data.
SMALL-SCALE STRUCTURE OF THE ZODIACAL DUST CLOUD OBSERVED IN FAR-INFRARED WITH AKARI
TAKAFUMI OOTSUBO,YASUO DOI,SATOSHI TAKITA,SHUJI MATSUURA,MITSUNOBU KAWADA,TAKAO NAKAGAWA,KO AROMATSU,MASAHIRO TANAKA,TORU KONDO,DAISUKE ISHIHARA,Fumihiko Usui,MAKOTO HATTORI 한국천문학회 2017 天文學論叢 Vol.32 No.1
The zodiacal light emission is the thermal emission from the interplanetary dust and the dominant diffuse radiation in the mid- to far-infrared wavelength region. Even in the far-infrared, the contribution of the zodiacal emission is not negligible at the region near the ecliptic plane. The AKARI far-infrared all-sky survey covered 97\% of the whole sky in four photometric bands with band central wavelengths of 65, 90, 140, and 160~$\mu$m. AKARI detected the small-scale structure of the zodiacal dust cloud, such as the asteroidal dust bands and the circumsolar ring, in far-infrared wavelength region. Although the most part of the zodiacal light structure in the AKARI far-infrared all-sky image can be well reproduced with the DIRBE zodiacal light model, there are discrepancies in the small-scale structures. In particular, the intensity and the ecliptic latitude of the peak position of the asteroidal dust bands cannot be reproduced precisely with the DIRBE models. The AKARI observational data during more than one year has advantages over the 10-month DIRBE data in modeling the full-sky zodiacal dust cloud. The resulting small-scale zodiacal light structure template has been used to subtract the zodiacal light from the AKARI all-sky maps.
AKARI FAR-INFRARED ALL-SKY SURVEY MAPS
Doi, Yasuo,Komugi, Shinya,Kawada, Mitsunobu,Takita, Satoshi,Arimatsu, Ko,Ikeda, Norio,Kato, Daisuke,Kitamura, Yoshimi,Nakagawa, Takao,Ootsubo, Takafumi,Morishima, Takahiro,Hattori, Makoto,Tanaka, Masa The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
Far-infrared observations provide crucial data for the investigation and characterisation of the properties of dusty material in the Interstellar Medium (ISM), since most of its energy is emitted between ~ 100 and $200{\mu}m$. We present the first all-sky image from a sensitive all-sky survey using the Japanese AKARI satellite, in the wavelength range $50-180{\mu}m$. Covering > 99% of the sky in four photometric bands with four filters centred at $65{\mu}m$, $90{\mu}m$, $140{\mu}m$, and $160{\mu}m$ wavelengths, this achieved spatial resolutions from 1 to 2 arcmin and a detection limit of < 10 MJy $sr^{-1}$, with absolute and relative photometric accuracies of < 20%. All-sky images of the Galactic dust continuum emission enable astronomers to map the large-scale distribution of the diffuse ISM cirrus, to study its thermal dust temperature, emissivity and column density, and to measure the interaction of the Galactic radiation field and embedded objects with the surrounding ISM. In addition to the point source population of stars, protostars, star-forming regions, and galaxies, the high Galactic latitude sky is shown to be covered with a diffuse filamentary-web of dusty emission that traces the potential sites of high latitude star formation. We show that the temperature of dust particles in thermal equilibrium with the ambient interstellar radiation field can be estimated by using $90{\mu}m$, $140{\mu}m$, and $160{\mu}m$ data. The FIR AKARI full-sky maps provide a rich new data set within which astronomers can investigate the distribution of interstellar matter throughout our Galaxy, and beyond.
THE FILAMENTARY WEB OF STAR FORMATION
White, Glenn J.,Doi, Yasuo,Komugi, Shinya,Kawada, Mitsunobu,Takita, Satoshi,Arimatsu, Ko,Ikeda, Norio,Kato, Daisuke,Kitamura, Yoshimi,Nakagawa, Takao,Ootsubo, Takafumi,Morishima, Takahiro,Hattori, Mak The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
Following the first Public Release of the AKARI Point Source catalogues, we have worked on the production of a new far-infrared All-Sky Diffuse mapping product. In this paper we report first results from the All Sky diffuse maps that will shortly be released to the community, based on analysis of data from the Far Infrared Surveyor ($65{\mu}m-160{\mu}m$) instrument. These data are likely to have a strong impact on studies of extended structures, and the diffuse ISM.
THE 18 ㎛ LUMINOSITY FUNCTION OF GALAXIES WITH AKARI
Toba, Yoshiki,Oyabu, Shinki,Matsuhara, Hideo,Ishihara, Daisuke,Malkan, Matt,Wada, Takehiko,Ohyama, Youichi,Kataza, Hirokazu,Takita, Satoshi The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We present the $18{\mu}m$ luminosity function (LF) of galaxies at 0.006 < z < 0.8 (the average redshift is ~ 0.04) using the AKARI mid-infrared All-Sky Survey catalogue. We have selected 243 galaxies at $18{\mu}m$ from the Sloan Digital Sky Survey (SDSS) spectroscopic region. These galaxies then have been classified into five types; Seyfert 1 galaxies (Sy1, including quasars), Seyfert 2 galaxies (Sy2), low ionization narrow emission line galaxies (LINER), galaxies that are likely to contain both star formation and Active Galactic Nuclei (AGN) activities (composites), and star forming galaxies (SF) using optical emission lines such as the line width of $H{\alpha}$ or the emission line ratios of [OIII]/$H{\beta}$ and [NII]/$H{\alpha}$. As a result of constructing the LF of Sy1 and Sy2, we found the following results; (i) the number density ratio of Sy2 to Sy1 is $1.64{\pm}0.37$, larger than the results obtained from optical LF and (ii) the fraction of Sy2 in the entire AGN population may decrease with $18{\mu}m$ luminosity. These results suggest that most of the AGNs in the local universe are obscured by dust and the torus structure probably depends on the mid-infrared luminosity.
Yoshiki Toba,SHINKI OYABU,Hideo Matsuhara,DAISUKE ISHIHARA,Matt A. Malkan,Takehiko Wada,YOUICHI OHYAMA,Hirokazu Kataza,SATOSHI TAKITA,Chisato Yamauchi 한국천문학회 2017 天文學論叢 Vol.32 No.1
We demonstrate the luminosity dependence of the covering factor (CF) of active galactic nuclei (AGNs), based on AKARI mid-infrared all-sky survey catalog. Combining the AKARI with Sloan Digital Sky Survey (SDSS) spectroscopic data, we selected 243 galaxies at 9 $\mu$m and 255 galaxies at 18 $\mu$m. We then identified 64 AGNs at 9 $\mu$m and 105 AGNs at 18 $\mu$m by their optical emission lines. Following that, we estimated the CF as the fraction of type 2 AGN in all AGNs. We found that the CF decreased with increasing 18 $\mu$m luminosity, regardless of the choice of type2 AGN classification criteria.